Field of the Invention
The present invention relates to an image forming apparatus, which includes a transfer unit including a belt configured to transfer a toner image from an image bearing member onto a transfer material and a cleaning unit configured to remove residual toner on the belt.
Description of the Related Art
In Japanese Patent No. 3815139, there is disclosed an image forming apparatus, which includes an image forming unit including an image bearing member configured to bear a toner image and a transfer unit including a belt configured to transfer the toner image from the image bearing member onto a transfer material. According to the configuration of Japanese Patent No. 3815139, residual toner on the belt is removed by a cleaning member.
In recent years, further downsizing is demanded of image forming apparatuses. Further downsizing is also demanded for a cleaning unit. In order to downsize the cleaning unit, the longitudinal width of a cleaning member needs to be reduced. However, the longitudinal width of the cleaning member needs to be larger than the longitudinal width of a developing member of an image forming unit. When this relationship is not satisfied, a toner image which cannot be removed may remain on a belt of a transfer unit and cause an image defect. Thus, in order to reduce the longitudinal width of the cleaning member of the cleaning unit, a relative positional relationship with the image forming unit needs to be determined with high accuracy.
However, according to Japanese Patent No. 3815139, the cleaning unit is positioned and fixed with respect to the transfer unit, and the image forming unit is fixed to an apparatus main body. Thus, a plurality of components are interposed between the cleaning member, which is a key component of the cleaning unit, and the image forming unit. That is, components such as the apparatus main body of the image forming apparatus, the transfer unit, and a casing of the cleaning unit are interposed, with the result that dimensional tolerances and mounting errors of those components in the longitudinal direction are imposed. Therefore, the longitudinal width of the cleaning member needs to be determined in consideration of those errors, and there is difficulty in reducing the longitudinal width of the cleaning member.